Abstract The objective of the Biospecimen Unit is to provide the necessary infrastructure to prospectively acquire the highest quality human tumor specimens to support the mission of the Center for Pediatric Tumor Cell Atlas (CPTCA). Our existing biorepository infrastructure is modern, stream-lined and highly supported by our institution. Our leadership role in several similar, large scale multi-institutional projects have changed the therapeutic approach and standard of care of specific pediatric cancers and provide further evidence that the structure is already in place to ensure the success of CPTCA. We will prospectively collect tumor and blood samples from twenty patients for three major pediatric cancers. We propose the following three specific aims: 1) To acquire, process and characterize pediatric high-grade glioma biospecimens for the CPTCA examining the critical genomic transitions from diagnosis to relapse; 2) To acquire, process and characterize pediatric high-risk neuroblastoma biospecimens for the CPTCA to define tumor evolution and the clonal dynamic response to chemotherapy and targeted therapy; 3) To acquire, process and characterize pediatric very high-risk B-cell acute lymphoblastic leukemia (VHR ALL) biospecimens for the CPTCA for the evolution of disease through standard therapy and CAR-T cell immunotherapy. At the completion of this aim, we will provide high quality biospecimens to the Characterization Unit for comprehensive multi-omic and in situ analyses integrated with a highly annotated clinical, molecular, pathologic and radiographic database.